mm/rmap: use rmap_walk() in page_referenced()
Now, we have an infrastructure in rmap_walk() to handle difference from
variants of rmap traversing functions.
So, just use it in page_referenced().
In this patch, I change following things.
1. remove some variants of rmap traversing functions.
cf> page_referenced_ksm, page_referenced_anon,
page_referenced_file
2. introduce new struct page_referenced_arg and pass it to
page_referenced_one(), main function of rmap_walk, in order to count
reference, to store vm_flags and to check finish condition.
3. mechanical change to use rmap_walk() in page_referenced().
[liwanp@linux.vnet.ibm.com: fix BUG at rmap_walk]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/ksm.c b/mm/ksm.c
index 646d45a..3df141e 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1891,61 +1891,6 @@
return new_page;
}
-int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg,
- unsigned long *vm_flags)
-{
- struct stable_node *stable_node;
- struct rmap_item *rmap_item;
- unsigned int mapcount = page_mapcount(page);
- int referenced = 0;
- int search_new_forks = 0;
-
- VM_BUG_ON(!PageKsm(page));
- VM_BUG_ON(!PageLocked(page));
-
- stable_node = page_stable_node(page);
- if (!stable_node)
- return 0;
-again:
- hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
- struct anon_vma *anon_vma = rmap_item->anon_vma;
- struct anon_vma_chain *vmac;
- struct vm_area_struct *vma;
-
- anon_vma_lock_read(anon_vma);
- anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,
- 0, ULONG_MAX) {
- vma = vmac->vma;
- if (rmap_item->address < vma->vm_start ||
- rmap_item->address >= vma->vm_end)
- continue;
- /*
- * Initially we examine only the vma which covers this
- * rmap_item; but later, if there is still work to do,
- * we examine covering vmas in other mms: in case they
- * were forked from the original since ksmd passed.
- */
- if ((rmap_item->mm == vma->vm_mm) == search_new_forks)
- continue;
-
- if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
- continue;
-
- referenced += page_referenced_one(page, vma,
- rmap_item->address, &mapcount, vm_flags);
- if (!search_new_forks || !mapcount)
- break;
- }
- anon_vma_unlock_read(anon_vma);
- if (!mapcount)
- goto out;
- }
- if (!search_new_forks++)
- goto again;
-out:
- return referenced;
-}
-
int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
{
struct stable_node *stable_node;
@@ -1954,6 +1899,11 @@
int search_new_forks = 0;
VM_BUG_ON(!PageKsm(page));
+
+ /*
+ * Rely on the page lock to protect against concurrent modifications
+ * to that page's node of the stable tree.
+ */
VM_BUG_ON(!PageLocked(page));
stable_node = page_stable_node(page);